The Australian wildcard's gallant Open campaign ground to a frustrating end with a tough third-round loss to seeded Italian Luciano Darderi.
Sweeny complained of a hip injury during a 6-4 6-3 6-3 defeat to the world No.22 that left Australia without a second-week singles hope in New York for the first time in five years.
The 25-year-old lamented not being able to replicate his sizzling second-round form, which yielded the scalp of world No.13 and dual grand slam semi-finalist Lorenzo Musetti, but was otherwise chuffed with his breakout run.
"It's been an amazing week, a career-changing week," Sweeny told AAP.
"But I can't help but feel a bit disappointed just with today's performance. I just wasn't really feeling it, not really feeling the timing and the rhythm as I have been.
"Just made a lot of cheap errors and that was quite frustrating. I was OK to lose a match, but I really wanted to test him more and bring a good level so I could make an absolute fight out of it.
"Win or lose, I wanted to really make him work for the victory at least and I wasn't able to do that."
Alex de Minaur's shock second-round loss to Botic van de Zandschulp had left Sweeny as Australia's last man standing at Flushing Meadows.
The world No.123 only gained a last-minute entry to the season's last major after two late withdrawals allowed Tennis Australia to grant Sweeny the reciprocal wildcard they initially intended on handing to Alexei Popyrin.
When Popyrin instead gained a start courtesy of his ranking, Sweeny was able to cash in on his sliding doors opportunity.
The 25-year-old will walk away with a cheque for $US290,000 ($A402,800) - which represents about a quarter of his entire career on-court earnings - for reaching the last 32 of a grand slam for the first time.
"I'll actually be able to put some money in the bank," Sweeny said.
"My brother's a financial advisor, so I'll just give him all the money. Maybe (buy) a little bit of property or something. I don't know."
Sweeny will most likely reinvest in his tennis.
The Queenslander is already reaping the rewards for hiring former Australian Davis Cup player Peter Luczak as coach this American summer.
"Dane couldn't afford a proper coach until this year," Sweeny's sister Emma posted on social media on Sunday.
"Dad had never played tennis himself, but he sold his business for peanuts, gave up so much and did everything he could because he believed in his son and his dream.
"This is only the beginning, Dane."
Sweeny added: "I'm always investing back in my tennis. That's the No.1 goal, to do all I can to be the best player I can be, so money I don't really worry about spending on my tennis."
Sweeny is also guaranteed a fresh career-high ranking and is provisionally slated to climb to No.109 in the world.
If he can crack the top 100 by season's end, the Sunshine Coast star will earn direct entry to the Australian Open for the first time.
"That's exciting too. But that will take care of itself," Sweeny said.
"It's hard not to to worry about that because we're indoctrinated to want that low number next to our name, but I can just focus on working hard, focus on improving.
"Particularly just staying really kind to myself and trying to enjoy the journey.
"Beating a top-15 player here and reaching the third round, I can take a lot of confidence from this week. But I don't think this is my ceiling at all. I've got a lot to go."
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